Phage cocktail administration to reduce Salmonella load in broilers.

Salmonella is a serious foodborne pathogen that can cause gastrointestinal disease through the consumption of contaminated foods; including poultry meat. Salmonella is commonly present in the intestinal tract of poultry and farm environments, posing a potential risk of contamination during the processing of poultry meat. This study was a continuation in evaluating the effects of our previously developed phage cocktail targeting Salmonella at large-scale trials in commercial broiler farms, in which this cocktail considerably lowered Salmonella colonization in the gut of broilers. The phage cocktail given to broilers showed resistance to temperatures of up to 65 °C (> 60% survivability), pH ranging from 2 to 12 (> 96% survivability), 0.5 to 15% (w/v) NaCl (> 98% survivability), chlorine up to 0.5% (v/v) (53% survivability), and chlorine neutralizer (100% survivability). In the animal challenge study, phage treatments, designed as "prevention" and "exclusion" programs, could control Salmonella on day 20 and 32 of the experiment, respectively; as indicated by the absence of Salmonella detection in cloacal swabs from broilers (0% prevalence). In the commercial-scale trial I, Salmonella was not detected in the phage-treated group from cloacal swabs, boot cover swabs, and bedding material samples after 16 days (0% prevalence) of phage administration. In the commercial-scale trial II, phage treatment extended the Salmonella control period in broilers during a 40-day growout period. In summary, a phage cocktail demonstrated high efficiency in controlling various serovars of Salmonella historically linked to contamination on these broiler farms. Phage cocktail application offers an effective, alternative to enhance food safety within the poultry value chain, protecting consumers and as well as the economic sustainability of the poultry sector.